Biopsychology- Bio Rhythms: Infradian And Ultradian Rhythms Flashcards
(41 cards)
Infradian rhythm -
A type of biological rhythm with a frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder.
Ultradian rhythm -
A type of biological rhythm with a frequency of more that one cycle in 24 hours, such as the stages of sleep.
What is an example of an infradian rhythm in females?
The female menstrual cycle is an example of an infradian rhythm, governed by monthly changes in hormone levels that regulate ovulation.
What does the menstrual cycle refer to?
It refers to the time between the first day of a woman’s period, when the womb lining is shed, to the day before her next period.
How long does a typical menstrual cycle take to complete?
Approximately 28 days, though 24 to 35 days is generally considered normal.
What happens during each menstrual cycle in terms of hormones?
Rising levels of oestrogen cause the ovary to develop an egg and release it (ovulation), and after ovulation, progesterone helps the womb lining grow thicker in preparation for pregnancy.
What happens if pregnancy does not occur?
The egg is absorbed into the body, the womb lining comes away, and it leaves the body as menstrual flow.
What study suggests the menstrual cycle can be influenced by exogenous factors?
A 1998 study by Kathleen Stern and Martha McClintock demonstrated menstrual cycle synchronisation through female pheromones.
How was the McClintock study conducted?
29 women with irregular periods participated. Pheromone samples from 9 women were collected via cotton pads placed in their armpits and worn for at least 8 hours.
How were the pheromone samples used in McClintock’s study?
The pads were treated with alcohol, frozen, and then rubbed on the upper lips of the other 20 participants across successive days, matching the cycle day of the donor.
What did McClintock find in her study?
68% of the women experienced changes to their menstrual cycles which brought them closer to their donor’s cycle.
What is SAD and how is it classified?
Seasonal Affective Disorder is a depressive disorder with a seasonal pattern of onset, listed in the DSM-5.
What are the symptoms of SAD?
Persistent low mood, general lack of activity, and reduced interest in life.
Why is SAD also known as the “winter blues”?
Because its symptoms are triggered during the winter months when daylight hours are shorter.
How is SAD classified rhythmically?
It is a type of infradian rhythm called a circannual rhythm due to its yearly cycle, but can also be considered a circadian rhythm due to the sleep/wake cycle disruption.
What hormone is implicated in the cause of SAD?
Melatonin, which is secreted by the pineal gland during darkness.
How does melatonin secretion in winter contribute to SAD?
In winter, the lack of morning light prolongs melatonin secretion, which may reduce serotonin levels, leading to depressive symptoms.
What is an example of an ultradian rhythm?
The stages of sleep, also known as the sleep cycle.
How long does a full sleep cycle last?
Approximately 90 minutes, repeating throughout the night.
How is brainwave activity during sleep measured?
Using an EEG (electroencephalogram).
What occurs during stages 1 and 2 of sleep?
Light sleep where the person is easily woken; brainwaves become slower and more rhythmic (alpha and theta waves).
What occurs during stages 3 and 4 of sleep?
Deep sleep or slow wave sleep, characterised by slow delta waves with greater amplitude, and it is difficult to wake someone at this point.
What happens during stage 5 of sleep?
REM sleep: the body is paralysed, but brain activity speeds up and resembles that of an awake brain.
Why is REM sleep called that?
REM stands for Rapid Eye Movement, indicating fast eye activity under closed eyelids.
